Pivot mold assembly method

ABSTRACT

The following specification describes a stop boss formed on the handle of a pail by means of a pair of slides located behind a skirt wall of the pail with the handle passing through a slot in the skirt wall, which is closed by a flange wall formed by the slides. The slides are movably carried in guides by a ring member and are received in a recess of another ring member which conventionally forms the annular pail wall. The guides enable the slides to move laterally toward each other in response to downward movement of the carrying ring member, to define the cavities for forming the stop boss and the flange wall closing the skirt wall slot. On completion of the mold cycle and upward movement of the ring member carrying the slides, the guides move the slides laterally apart to release the stop boss and the flange wall. The slides are then moved from between the skirt and pail walls to enable the pail to be released from the mold.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 781,631 filed Mar. 28, 1977,now U.S. Pat. No. 4,114,849.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to apparatus for molding a pivot andmore particularly to an improved apparatus and method for molding aninternal pail pivot and the improved article formed thereby.

In my copending application Ser. No. 739,198, filed Nov. 5, 1976, nowabandoned, there is disclosed a mold and method for molding a freelypivotable bail on a bucket or can, simultaneously with the molding ofthe bucket. The mold incorporates a ring member for forming internal andexternal bearing surfaces on the bail or handle and on the bucketrespectively. After the bearing surfaces are formed, the ring member ismoved axially or radially of the bucket past a bail retaining member.This movement is provided by hydraulically operated members which extendinto a mold passageway, thereby presenting a somewhat complicated andexpensive mold arrangement, while a relatively large spacing between theinner and outer bearing surfaces is required to receive the ring member.

2. Summary of the Invention

The present invention utilizes an extremely simple and ingeniousarrangement for enabling the molding of an internal, freely pivotablehandle on a pail, bucket, or can. This is done by molding the handle orbail through a passage in a skirt wall spaced from the pail wall, andmolding a stop boss on the handle to prevent retraction of the handlethrough the passage. The passage or slot is closed at opposite ends.

To provide this arrangement without the use of additional hydraulicallymovable members, as disclosed in the aforementioned application, thepresent invention makes use of the conventionally movable upper andlower mold rings forming the annular wall of the pail. The lower ring isprovided with a recess for receiving a downwardly extending pair ofslides on the upper ring for forming the skirt wall therebetween and thepassage through which the handle extends.

Intermediate the skirt and pail walls, the slides are moved laterally byguideways of the upper ring in response to downward movement of theupper ring until they engage to form the mold cavity for the stop bosson the handle and the cavity forming a flange wall closing the skirtwall passage.

On opening the mold the upper ring moves upwardly to move the slideslaterally, and when they are spaced sufficiently to clear the stop bossand the slot closing wall, they are also retracted from the recess inthe lower ring to enable release of the pail.

It is therefore one object of the present invention to provide animproved mold and/or method for forming a pivot assembly.

It is another object of the present invention to provide an improvedmold and/or more economical method for forming a freely rotatable bailon a pail.

It is still another object of the present invention to provide a moreeconomical assembly of a plastic pail and a freely rotatable plasticbail.

Other objects and features of the present invention will become apparenton examination of the following specification and claims together withthe drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial sectional view taken along line 1--1 of FIG. 2,illustrating the relevant portions of a mold assembly incorporating theprinciples of the present invention;

FIG. 1a is a partial sectional view taken along line 1a--1a of FIG. 2;

FIG. 2 is a bottom plan view of the upper ring portion of the upper moldassembly;

FIG. 3 is a side elevational view of a pail formed in the mold assemblyshown in FIG. 1 and incorporating the principles of the presentinvention;

FIG. 4 is an enlarged fragmentary front view of the retaining boss onthe pail wall;

FIG. 5 is an enlarged fragmentary side view of the retaining boss shownin FIG. 4;

FIG. 6 is a bottom elevational view of the insert assembly of the upperring;

FIG. 7 is a front elevational view of the insert assembly in raised openposition;

FIG. 8 is a front elevational view of the insert assembly in closedmolding position with a portion of the lower ring shown diagramaticallyrotated 90° from FIG. 1a;

FIG. 9 is a side elevational view of the insert assembly;

FIG. 10 is a diagramatic perspective view of the insert assembly inraised position together with a relevant portion of the lower ring; and

FIG. 11 is a perspective broken sectional view of the insert assembly inclosed molding position together with an exploded relevant portion ofthe lower ring.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The relevant portion of a mold assembly incorporating the principles ofthe present invention is indicated by the reference character 10 inFIG. 1. The assembly 10 is shown in section taken along transversediametric planes and includes an upper mold assembly 12, a lower splitring assembly 14 and an inner core assembly 16.

Only a split ring portion 18 of the upper mold assembly 12 is shown;however, it will be understood that the upper mold assembly 12 includesa back wall assembly for portion 18 to form a cup shape and that thering assembly 14 mates or engages with an annular lower flange portion20 on ring 18 as seen in FIG. 1 along a parting line or surface 22. Theflange portion 20 together with the ring assembly 14 are seated in anannular recess 24 defined by a radially outwardly extending cap shapedflange 26 of the core assembly 16.

The cup shaped flange 26 has a rim wall 28 for seating or engaging aradial outward portion of assembly 12 along a horizontal parting line,and the recess 24 is formed at the radially inward end of the rim wall28 for seating flange 20 and ring 14. A radially inwardly and downwardlyextending inclined parting line 30 is formed by the tandem outerinclined peripheral surfaces of flange 20 and ring 14 engaging theinclined axially extending surface of recess 24. In addition, anannular, horizontal parting line or surface 32 is between the lowersurface of ring 14 and the bottom surface of flange 26.

The core assembly 16 has an axially projecting central portion 34received in the hollow space encircled by assembly 12 and ring 14 todefine therebetween a cup shaped mold cavity having an annular moldcavity portion 36 and forming a cup shaped plastic bucket, can or pail38 seen in FIG. 3 with an annular wall 40 formed in mold cavity 36. Ahandle 42 is formed for the pail 38 in a mold cavity 44 defined byfacing recesses in the lower surface of flange 18 and the upper surfaceof ring 14. Each end of the handle 42 is supported and secured forfreely rotatable movement in a respective one of a pair of diametricallyopposed or spaced hollow retaining bosses such as 46 formed on theannular wall 40 of the pail 38 at a position spaced from but adjacent tothe open end 48 of the pail.

The hollow retaining boss 46 includes a top wall 50 and spaced sidewalls 52 extending radially outwardly from the annular pail wall 40 andjoined at their radial outward end by a retaining skirt or front wall 54to define an open bottom for the recess formed by the hollow boss 46.Radially outwardly extending annular walls 56 are also formed on annularpail wall 40 in a cavity 58 and each wall 56 extends from one side wall52 of one boss 46 to a side wall 52 of the outer boss 46. Otherrigidifying, radially outwardly extending annular walls may be formed onwall 40 intermediate the hollow bosses 46 and open end 48 if desired bysuitable mold cavities at the radial inward end of ring 14 and incommunication with mold cavity 36.

The skirt or retaining wall 54 of each boss 46 is provided with apassage or slot 60 located intermediate the spaced end or side walls 52for passing or rotatably supporting an adjacent portion of the handle42. One end of the slot 60 is closed adjacent the top wall 50 by aportion of retaining wall 54 and movement from the other or open end ofthe slot 60 is prevented by a flange wall 62 extending radially betweenan annular pail wall 40 and retaining wall 54, and integrally joinedthereto adjacent the lower opposite edges of the slot 60 to form a rigidretaining boss for the rotatable handle 42. Thus wall 54 is connected atpositions spaced circumferentially of handle 42 to the annular pailwall. The various orientations and directions described with referenceto the boss 46 are those normally applied in use of the pail. However,it will be understood that the pail may be molded in an upside downposition and that therefore the parts in the mold will normally belocated in a position opposite to those described above so that, asshown in FIG. 1, the parts for forming the boss may hereafter generallybe described with an opposite orientation.

The portion of the handle 42 passing through the slot 60 is providedwith an enlarged, cylindrically shaped stop boss 64 formed adjacent thehandle end intermediate the pail wall 40 and retaining wall 54. The stopboss 64 has a larger diameter or peripheral dimension than the spacebetween opposite edges of slot 60, wherefore it cannot be retractedthrough the slot, and walls 54 and 62 confine its movement to betweenthe ends of slot 60.

To form each hollow retaining boss 46 and the stop boss 64, with thepail 40, in single molding operation, the present invention employs aninsert assembly 66 for each boss 46, located in diametrically opposite,radially extending slots 68 defined in the lower flange 20 on ringportion 18. Each insert assembly 66 comprises a support block 70extending radially of the mold cavity 36 and secured to ring 18 by afastening member extending through a rectangular boss 72, seated in acorresponding shaped recess of ring 18.

A pair of dovetail guides or guideways 74 are formed adjacent theradially inward end of block 70 as seen in FIGS. 6-10. These extendthrough a depending leg 76 on block 70 for guiding the movement of apair of identical stop boss forming members or slides 78 each having arespective T-shaped or dovetail key 80 engaged in a respective one ofthe guides 74.

The guides or cams 74 extend vertically downwardly from the top of block70 as seen in the drawings or axially of the cavity 36 from a positionadjacent the central radially extending vertical plane of block 70toward a respective outer vertical side surfaces or margins of thedepending leg 76, so that they are each inclined to form adjacent legsof a triangle. The upper portion of each guide 74 has an enlargedparallel recess 82 to receive a respective stop pin 84 projectingoutwardly from each key 80. The pins 84 each engage a stop wall 86formed at the lower end of each enlarged recess 82 located intermediatethe top and bottom ends of block 70 for lifting the respective slidemember 78, when ring 18 is raised a predetermined distance on openingthe mold as will be explained.

The members 78 each have a perimeter shape generally corresponding to aright triangle and are adapted to engage along the elongate right angleedge 88 generally coincident with the central vertical plane of block70. A stepped cylindrical recess 90 in each edge 88 defines matinghalves of a mold cavity 92, communicating at the radially inward endwith annular cavity 36, to form the stop boss 64 and adjacent portionsof the handle 42. At its radially outward end, cavity 92 communicateswith a cavity portion 96 formed on a leg 98 extending into a slot 100between leg 76 and block 70.

The lower portion of retaining wall 54 is formed in the slot 100 and theleg 98 forms a corresponding portion of the slot 60 in the retainingwall 54. The lower edge of leg 98 engages the upper surface of aprojecting member 102 best seen in FIG. 11, on ring 14 to form theremainder of the slot 60, and a recess 104 in the projecting member 102defines with recess 96 a mold cavity for the handle 42, which projectsthrough the slot 60. The recesses 96 and 104 in turn communicate withrecesses in block 70 and ring 14 defining handle cavity 44. A secondrecess 106 in each vertical edge 88 defines a mold cavity 108 forforming the flange wall 62 in communication with cavity 36 and with slot100 at opposite side of leg 98 to join wall 62 to the lower edge of wall54.

The lower corners of members 78 are spaced inwardly of the side verticalmargins or edges of the depending leg 76. When the block 70 is raisedwith ring 18, the members 78 follow the guides 74 to space the edges 88by a distance greater than the diameter of retaining or stop boss 64 andwall 62, as will be explained.

The leg 76 and the lower portion of members 78 are received in agenerally rectangular recess 110 located at the radially inward end ofring 14 and in the upper surface thereof. A pair of spaced stop members112 extend upwardly from the bottom wall of recess 110 and from thefront vertical surface 114 of the recess 110 toward the mold cavity 36but terminate at a position spaced from the mold cavity 36. The stopmembers 110 each engage the bottom surface of members 78 to space themembers 78 from the bottom wall of the recess 110. This has the effectof driving the members 78 upwardly relative the leg 76 in response tothe downward movement of leg 76 for enabling the edges 88 to meet onclosure of the mold, as will be explained.

The spacing between the bottom surfaces of members 78, leg 76, and thebottom surface of recess 110 forms a mold cavity 114 best seen in FIGS.1 and 8 in which the top wall 50 of boss 46 is formed at an angle ofsubstantially 15 degrees to the horizontal axis as the bottom surfacesof recess 110 and of leg 76 and members 78 are formed at a correspondingangle. The stops 112 form correspondingly shaped slots 116 in the boss46. The side edges or surfaces of leg 76 are spaced from the side orradial margins of recess 110 and from radially extending side portionsof the slot 68 in ring member 18 to define mold cavities 120 incommunication with mold cavities 38 and 114 for forming side walls 52 ofthe boss 46.

The margin or outer surface of projection 102 tapers inwardly towards aflat front surface for engagement with the surface of members 78 andprojects through the wall 54 of the boss 46.

The mold 10 is conventionally operated by assembling ring members asshown in FIG. 1 to form the cup shaped mold cavity including the annularmold cavity 36 for forming wall 40. Ring member 14 is received in recess24, whereafter the assembly 12, including ring 18 and flange 20 carryingassembly 66, are moed downwardly for engagement with ring 14.

The slides 78 are normally extended from leg 76 during the downwardmovement and held from disengagement by stop pins 84, engaged with stopwalls 86. As descent of ring 18 continues, the bottom surfaces of slides78 engage stops 112 in recess 110. The continued downward movement ofblock 70 drives the slides 78 toward each other under the influence ofthe guide surfaces 74.

The leg 76 descends, until the vertical edges 88 of slides 78 engage toform cavities 92 and 108 with the leg 76 positioned in the recess 110and the lower edge of leg 76 engages the upper surface of projector 102for defining the mold cavities in which the boss 46 together with theboss 64 and handle are formed.

A plastic molding powder or similar substance is then injected into themold cavity 38 generally through a passage (not shown) in the back wallof assembly 12 and the powder flows through the cavity 36 into cavity92, 108, 114 and 120 to form boss 46. Thereafter the mold is opened inany wall known manner to move ring 18 upwardly.

A ring 18 and the leg 76 moves up, the slides 78 are cammed from eachother, pulled by the plastic part itself along the guides 74 to moveedges 88 apart. The slides 78 separate by a distance permitting theedges of mold cavities 92 and 108 to clear the boss 64 and wall 62respectively. Pins 84 then engage stop walls 86 and the slides 78 arelifted from recess 110 and from between walls 54 and 40.

The ring 40 may now be raised in any well known manner to free thebucket 38 from the mold cavity and the bucket 40 is then conventionallydisengaged from the ring 14.

The portion of the handle connecting the stop boss 64 with the annularpail wall 40 may have a diameter of only 0.045 inch, and does notprevent free rotation of the handle, since it either breaks off inresponse to rotatable movement or twists so easily as to permit fullrotation without any significant restraining force due to its smallsize.

The foregoing description relates to an improved method and mold forforming a pivot together with the article formed thereby, but theinventive concepts are not believed limited to the foregoing descriptionbut are believed covered in the accompanying claims.

What is claimed is:
 1. A method for forming a retaining portioncomprising first and second molded walls about a freely pivotable memberextending through a passage formed in said first molded wall to occupy aposition intermediate said first wall and second molded wall, saidsecond molded wall being spaced from said first wall and integrallyinterconnected with said first wall at a plurality of positions spacedcircumferentially about said pivotable member, to define a recessbetween said first and second walls, comprising the steps of:positioningmold means to define and form said first and second walls and saidpivotable member, positioning a pair of mold members in said recessbetween said first and second walls to define a mold cavity for formingsaid retaining portion about said pivotable member; forming saidpivotable member and said retaining portion in said cavity about saidpivotable member; and thereafter spacing said mold members from eachother and from said retaining portion to enable retraction of said moldmembers from between said first and second walls.
 2. The method of claim1 including the step of forming a portion of said retaining memberwithin said recess with a larger dimension than said passage, to preventremoval of said pivotable member through said passage.
 3. The method ofclaim 2 including the steps of defining a mold cavity between said moldmembers for forming a flange wall connected to said second wall toprevent retraction of said pivotable member from said passage, formingsaid flange wall, and thereafter spacing said mold members from saidflange wall.
 4. The method of claim 3 including the step of forming saidsecond wall as an annular wall, and said first wall as a skirt wall, andinterconnecting said annular wall at said spaced circumferentialpositions, with spaced side walls and with a top wall, simultaneouslywith said retaining portion and said flange wall.
 5. The method of claim4 including the step of forming said annular wall with a pair ofadjacent axially movable ring portions with one portion carrying saidpair of mold members, and the other ring portion defining a recess forreceiving said pair of members, and defining one surface of a moldcavity for forming said skirt wall and said side and top walls.
 6. Amethod for forming a pail having a freely rotatable handle in a molddefining a pair of ring members arranged for relative axial movementtherebetween to define an annular wall portion of said pail, theimprovement comprising the steps of:providing means movable with saidring members to define a cavity in which a retaining wall integrallyattached to said annular wall is formed with a closed-end slot in saidretaining wall; providing means movable with said ring members forforming a portion of said rotatable handle extending to said slot;providing boss-forming means carried by one of said ring membersdefining a mold cavity intermediate said retaining wall and said annularwall portion for forming a stop boss on said rotatable handle, toprevent retraction of said handle through said slot; forming said pail,retaining wall, handle, and boss; and moving portions of said bossforming means in opposite directions in response to relative axialmovement in one direction between said ring members, to space saidportions from said stop boss and retaining wall to retract said bossforming means from between said annular wall portion and said retainingwall.
 7. The method of claim 6 including defining a mold cavity forforming a flange wall extending radially between said annular wallportion and said retaining wall for preventing movement of said memberpast the one end of said slot.
 8. In the method claimed in claim 6, thestep of moving said boss forming portions toward each other in responseto relative axial movement of said ring members in the oppositedirection to form said boss mold cavity and flange mold cavity.